Well, streams are generally the hardest to do for beginners, so no worries.
The only way to get better at them is to play streams everyday, preferably of all BPMs. 186 BPM streams like your map are already quite fast, but you don't need as much finger control (imo) for them like with slow BPM streams, so if you just play some 180-190BPM stream maps and watch it play on Auto, you should be able to figure out the tapping speed quickly and then just try to imitate it.
Download this:
https://osu.ppy.sh/b/149551&m=0and play the Himiko 185BPM. It has the pretty much the same tempo.
Again, watch Auto first, then maybe play it with RX mod, then just play it yourself with NF. Just resort to Auto whenever you forget what its supposed to "sound" like.
Enable the hit error bar at the bottom of the screen if you haven't and keep an eye on it when you do the streams so you can see if you hit too early / late and how close you are to hitting it perfectly.
If you are outside of the blue, its a 100 or 50, depending on the color.
Left means you're too early, right means you're too late. The white line in the middle of the blue bar is the perfect hit.
Also make sure you aren't just hitting the first note of the stream too early due to panic or something. It could be that you stream perfectly, but just started the stream to early, resulting in everything being 100s / 50s.
A good indicator to check if you're the right tempo despite hitting 100s is to look at the hit bar. If the hits (the transparent lines that appear on the bar when you hit a note / slider) are all very close to each other, then you have the right speed, but are just ahead / too late. Obviously if you screw up once and tap one or two times too fast, you'll be ahead of the stream, even if you do recover and keep the right tempo again, so you'd have to slow down for a split second and then pick up the same speed again to get 300s.
However, just try to hit the first note correctly and keep a steady tempo when doing streams, even if they end up all 100 you can check the hit bar to check what you did wrong.
And don't get spooked by the streams on this map. No matter if the stream is like 2 "streams" of each other or looks like a staircase, the tempo doesn't change. The tapping speed for a stream is ALWAYS the same, no matter the distance or shape of the notes.